Watson's dress leaves Potter fans spellbound

Harry Potter star Emma Watson turned on the magic with a barely-there dress as she bewitched fans at the world premiere of the latest Harry Potter blockbuster.

The actress donned a skimpy black lace mini-dress with a feathered skirt - showing a marked contrast to the prim and elegant outfits she has worn at the six previous Potter first nights.

Watson, 20, who stars as Hermione Grainger in the wizard series, blew kisses to fans who had camped out for hours in London’s Leicester Square for the occasion.

She was joined on the red carpet by 'Harry Potter And The Deathly Hallows Part 1' co-stars Daniel Radcliffe and Rupert Grint, who both wore smart suits for the launch.

'Deathly Hallows', the final Potter tale by author JK Rowling, has been split into two with the second film being screened next year.

In the new film, her character is seen kissing Harry Potter in a hallucination sequence.

Radcliffe, 21, has said he was surprised by how passionate Watson was while filming this scene.

Watson said: “I don’t know what to say. I suppose it had to be a kiss that would make Ron really jealous and so I think that’s why I was so passionate.”

Grint, now 22, said he thought the new film would shock fans.

He said: “I think they’ll be quite shocked. A lot of characters die and it’s quite scary. The whole world (of Harry Potter) is darker.”

JK Rowling said the film was her favourite of the series so far – which has generated billions of dollars in ticket revenues around the world.

She confirmed she was considering writing more books about the wizarding world but they would not feature Harry Potter.

She said: “If in 10 years’ time I wanted to do another one I probably would. However, I said to Dan (Radcliffe) I don’t think there will ever be another book with Harry as the central character. So Dan can sleep easy.”

Radcliffe admitted he had changed a lot in the 10 years he has been playing Harry Potter but said the films had given him direction.

The actor said: “When I started off on Potter I had no idea what I was getting into and 10 years later I’ve got direction in my life and I want to continue having a career in this.”

London's Leicester Square was transformed into a dark, smoke-filled crypt for the premiere with gravestones, mystic symbols and burning torches.

Death Eaters – mysterious cloaked figures wearing masks – patrolled the red carpet where fans waited for hours in the cold and rain to see the stars.

This year’s premiere seemed to break the “curse” of Harry Potter which has seen a number of previous launches lashed by rain.

Earlier Watson talked about her sense of style and how she had loved to choose her outfits from a young age.

She said: “My dad was very good when I was younger. He always encouraged me to choose things for myself. I was never just given clothes.

“From around six or seven, he would let me choose what I wanted to wear, so I always had my own identity. I have held on to that very strongly and refuse to be told what I should wear. If stylists work with me, they never just give me a dress and I’ll put it on.

“I have always had a strong sense of self and my convictions.”

The evening also saw her chat to a clearly smitten X Factor boy band One Direction on the red carpet.

'Deathly Hallows Part 1' is being released in Irish cinemas from November 19.